Brake



INVENTOR.

A TTORNE Y.

Aug- 17, 1943- c. L. EKSERGIAN BRAKE Filed Aug. 1, 1940 W a w W Patented Aug. 17, 1943 BRAKE Carolus L. Eksergian, Detroit, Mich., assignor to Budd Wheel Company, Philadelphia, Pa., a corporation of Pennsylvania Application August 1, 1940, Serial No. 349,057 5 Claims. (01. 188-78) This invention relates to improvements in brakes and more particularly in drum brakes of the internally expanding type,

An important object of this invention is to provide an improved brake shoe construction which is adapted to reduce the automatic interaction or servo action of interconnected brake shoes. thereby maintaining a more effective and uniform braking and reducing the tendency of one shoe to do most of the work, with resultant uneven wear or the brake linings.

Another object of the invention is to provide an improved brake shoe construction, more particularly of the internal expanding shoe construction in which one of the brake shoes is free to move circumferentially to a limited extent for servo action, but is restrained against vertical movement so that the efiective center of pressure is maintained substantially in the center of the brake shoe,

A still further and more detailed object of the invention is to provide an improved intermediate anchorage for a servo acting brake in which the anchorage has only a restrained movement, the restraint limiting the servo action on the other shoe.

Other objects and advantages will appear from the present specification of a preferred embodiment of the invention, reference being made to the accompanying drawing in which:

Fig. 1 is a partly sectional side elevation of a brake shoe supporting plate and actuating mech anism carried thereby, embodying the invention, the position of the brake drum being shown in dotted lines;

Fig. 2 is a fragmentary section taken substantially along the planes indicated by the broken line 2-2 of Fig. 1; and

Fig. 3 is a fragmentary section taken substantially along th plane indicated by the line 3--3 of Fig. 1.

In the various figures, similar elements are designated by the same reference characters.

In the specific embodiment of the invention selected herein for a disclosure, reference character 30 designates a brake backing plate, having a central hole 31, and bolt holes 21 spaced around same. The plate 30 is provided with a fixed stop or pin i2, serving as an anchorage for the primary brake shoe [6, and for the secondary brake shoe [5. The secondary shoe l5 carries a stud or pin ll constituting a pivot for the operating lever [8, which tends to spread the heel end I5a of shoe l5 away from the toe end Ilia of shoe I6 by a reaction acting through a link 20.

Said connecting link 20 may have a forked end I engaging a stud 2 mounted on the shoe l6, and a rounded portion 3 at its other end, engaging in a corresponding depression 4 in lever l8. The toe end l5b of the secondary shoe l5 and the heel end lfib of the primary shoe I6 are connected by links 22 and 2|, which are pivoted on a floating anchor 23 which is restrained in movement by a link 13, pivoted to the backing plate 30 by means of a stud or pivot pin I4.

The floating anchor, designated as a whole by 23, consists essentially of a cam or adjusting block 25, which may be forced between the ends of the links 2! and 22 by a screw-threaded adjusting member 26 having a squared end 40, as shown in Figs. 2 and 3. As will be understood, axial movement of the adjusting member 26 in the proper direction will cause the links 2i and. 22 to separate, to adjust the mechanism, as well as to take up any excessive play due to wear of the brake shoe linings 28.

The links 2| and 22 may be stampings, folded over as shown in Fig. 3 and preferably beaded longitudinally for stiifness, as shown at 35. The casing of anchorage 23 passes through an opening 38 in the plate 30 and at that place is effectively sealed against moisture by the gasket 36. It will be noted that a small amount of clearance is provided intentionally at 5, on one side of the anchorage, as shown in Fig. 3, to allow it to slide with respect to the backing plate 30.

The cam or block 25 is mounted in a tubular casing 8 having a lug or knob 6 formed thereon, and slidably engaged in a keyway or slot 1 of the block, to permit axial movement of the block 25 in said casing, but prevent rotation of the said block. Concavities 9 are formed in said block 25 to act as cams with respect to the convex ends I l of the links 2i and 22 which bear against the block 25. Slots l9 may be provided in the tubular casing 8, to receive the adjacent ends of the links 2| and 22 as shownin Figs. 2 and 3, and guide them, whil preventing them from becoming disengaged, or shifted axially of the casing, 8. At the remaining end, each link 2| and 22 is bifurcated as shown at 39, so as to engage a corresponding stud or pin 24 mounted in the brake shoes l5 and IS.

A return spring 29 having its ends 3! and 32 engaged in the openings 33 and 34 of the shoes,

is provided to retract the brake linings 28 from the drum ID.

The fixed center provided by the pivot I4 is located at one side of the diametral line on which the anchors l2 and 23 are arranged. toward one of the shoes, in the drawing the shoe 16 which is normally the leading shoe. The construction is such that the longitudinal axis of the link 22 and the link l3 are at an acute angle and intersect the adjacent shoe on opposite'sides of its center.

The operation of the brake is substantially as follows:

Assuming a counter-clockwise rotati n of the brake drum ID, the primary shoe 16 will tend to move in a counter-clockwise direction when its brake lining 2B is forced against the rotating drum l0, upon actuation of the operating lever l8. This incipient movement will be transmitted from the heel 15b along the link 22 to the anchor 23. Inasmuch as the anchor 23 is supported by the link l3, only a part of the force will be transmitted through the link 2| against the toe [5b of the secondary brake shoe l5. This automatically will reduce the force transmitted to the secondary shoe l5, by an amount dependent upon the relative angular positions of th said links, which determine what part of the force is sustained by the link l3. Furthermore, as the link l3 restrains the movement of the primary shoe I6,

the resulting effective center of brake shoe pressure will be intermediate the length of the brake shoe, thereby distributing the pressure and wear more nearly uniformly.

While a preferred embodiment of the invention has been disclosed herein in considerable detail, it should be understood distinctly that the invention is not limited to the specific embodiment disclosed but that certain changes, additions or omissions may be made therein without departing from the underlying principles. Therefore the scope of the present invention is defined solely in and by the following claims.

I claim:

1. A brake comprising a mounting plate, a pair of brake shoes carried thereby, a pair of anchors arranged at diametrically opposite points of said plate with which the adjacent shoe ends, respectively, coact, one of said anchors being fixed with respect to the mounting plate, means for expanding the shoes connected thereto adjacent their ends coacting with said fixed anchor, the other anchor being a floating anchor constrained to move about a fixed center disposed on the mounting plate a substantial distance to one side of the diameter on which the anchors are arranged, and links connecting the adjacent shoe ends with the floating anchor.

2. A brake comprising a mounting plate, a pair of brake shoes carried thereby, a pair of anchors arranged at diametrically opposite points of said plate with which the adjacent ends of the shoe ends, respectively, coact, one of said anchors being fixed with respect to the mounting plate, means for expanding the shoes connected thereto adjacent their ends coacting with the fixed anchor, the other anchor being a floating anchor constrained to move about a flxed center disposed on the mounting plate a substantial distance to the side of the diameter on which the anchors are arranged toward the shoe which is normally the leading shoe, and links connecting the adjacent shoe ends with the floating anchor.

3. A brake comprising a mounting plate, a pair of brake shoes carried thereby, a pair of anchors arranged at diametrically opposite points of said plate with which the adjacent shoe ends respectively, coact, one of said anchors being fixed with respect to the mounting plate, means for expanding the shoes connected thereto adjacent their ends coacting with the fixed anchor, the other anchor being a floating anchor constrained to move about a fixed cen'ter disposed on the mounting plate to one side of the diameter on which the anchors are arranged, and links connecting the adjacent shoe ends with the floating anchor, the longitudinal axis of the link associated with the shoe adjacent said center and a line passing through the floating anchor and the fixed center about which it is constrained to move being arranged at a. sharply acute angle with respect to each other.

4. A brake comprising a mounting plate, a pair of brake shoes carried thereby, a pair of anchors arranged at diametrically opposite points of said plate with which the adjacent shoe ends, respectively, coact, one of said anchors being fixed with respect to the mounting plate, means for expanding the shoes connected thereto adjacent their ends coacting with the fixed anchor, the other anchor being a floating anchor constrained to move about a fixed center disposed on the mounting plate to the side of the diameter on which the anchors are arranged toward th shoe which is normally the leading shoe, and links connecting the adjacent shoe ends with the floating anchor, the longitudinal axis of the link connecting the leading shoe and an extension of the line joining the floating anchor and the fixed center about which it is constrained to move intersecting the leading shoe on opposite sides of the center thereof.

5. A brake comprising a mounting plate, a pair of brake shoes carried thereby, a pair of anchors arranged at diametrically opposite points of said plate with which the adjacent shoe ends, respectively, coact, one of said anchors being fixed with respect to the mounting plate, means for expanding the shoes connected thereto adjacent their ends coacting with said fixed anchor, the other anchor being a floating anchor constrained to move about a fixed center disposed on said mounting plate at one side of the diameter on which the anchors are arranged, link connecting the adjacent shoe ends to the floating anchor, and means associated with one of said anchors for adjusting the shoes.

CAROLUS L. EKSERGIAN. 

